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// Copyright 2017 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ebitenutil
import (
"image/color"
"math"
"github.com/hajimehoshi/ebiten"
)
var (
emptyImage *ebiten.Image
)
func init() {
emptyImage, _ = ebiten.NewImage(16, 16, ebiten.FilterDefault)
_ = emptyImage.Fill(color.White)
}
func colorScale(clr color.Color) (rf, gf, bf, af float64) {
r, g, b, a := clr.RGBA()
if a == 0 {
return 0, 0, 0, 0
}
rf = float64(r) / float64(a)
gf = float64(g) / float64(a)
bf = float64(b) / float64(a)
af = float64(a) / 0xffff
return
}
// DrawLine draws a line segment on the given destination dst.
//
// DrawLine is intended to be used mainly for debugging or prototyping purpose.
func DrawLine(dst *ebiten.Image, x1, y1, x2, y2 float64, clr color.Color) {
ew, eh := emptyImage.Size()
length := math.Hypot(x2-x1, y2-y1)
op := &ebiten.DrawImageOptions{}
op.GeoM.Scale(length/float64(ew), 1/float64(eh))
op.GeoM.Rotate(math.Atan2(y2-y1, x2-x1))
op.GeoM.Translate(x1, y1)
op.ColorM.Scale(colorScale(clr))
// Filter must be 'nearest' filter (default).
// Linear filtering would make edges blurred.
_ = dst.DrawImage(emptyImage, op)
}
// DrawRect draws a rectangle on the given destination dst.
//
// DrawRect is intended to be used mainly for debugging or prototyping purpose.
func DrawRect(dst *ebiten.Image, x, y, width, height float64, clr color.Color) {
ew, eh := emptyImage.Size()
op := &ebiten.DrawImageOptions{}
op.GeoM.Scale(width/float64(ew), height/float64(eh))
op.GeoM.Translate(x, y)
op.ColorM.Scale(colorScale(clr))
// Filter must be 'nearest' filter (default).
// Linear filtering would make edges blurred.
_ = dst.DrawImage(emptyImage, op)
}
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